1. Field of the Invention
This invention relates, in general, to air conditioning apparatus to which a source voltage is supplied through a plug. In particular, the invention relates to an air conditioning apparatus which is used typically in individual house.
2. Description of the Prior Art
In general, electric household appliances, e.g., refrigerators, air conditioners, and so forth, have a plug through which a source voltage is supplied to the appliances.
In an air conditioning apparatus, the cooling/heating capacity thereof is closely related to the operating current (source current) which flows through the plug. Increase of the cooling/heating capacity will cause an increase of the operating current. However, the rated current of a wall outlet is set at a prescribed value, e.g., 15 A. If an operating current greater than the prescribed value flows for an extended period, the supply of the operating current through the wall outlet and the plug is normally stopped by a circuit breaker.
To prevent the excessive operation of the breaker, the maximum value of the operating current is maintained under the prescribed value in conventional apparatus. The current flowing through the plug is detected by a sensor. When the detected current is greater than the prescribed value, the capacity of the compressor is reduced, and therefore the operating current may be reduced below the prescribed value.
In addition, an insufficient connection between the wall outlet and the plug, loose terminals at the wall outlet, or surface corrosion of the terminals of the wall outlet or the plug often occurs during the use of such apparatus. If the operating current of the apparatus increases to the prescribed value under the condition described above, excessive heat occurs in the wall outlet and the plug of the apparatus. As a result, a tracking phenomenon in which the plastic materials of the wall outlet and the plug are carbonized occurs, and eventually a short circuit is established through the carbonized material of the wall outlet and the plug.
To solve the above problem, the maximum value of the operating current may be decreased below the prescribed value, for example, to 10 A. However, if the maximum value of the operating current is limited below the prescribed value, the desired cooling/heating capacity of the apparatus may not be obtained.